Phased array transmitters are typically composed of a regular two-dimensional array of radiating or transmitting elements. Each of these elements typically has an associated phase shifter. Beams are formed by shifting the phase of the signal emitted by each of the radiating elements. The result is constructive and destructive interference in the far field that enables the steering of the beam.
The same principle can be applied to phased array receivers. Similarly, a two-dimensional array of antenna or detection elements receives the incoming radiation. Their corresponding phase shifters shift the relative phase of the signals from each of the detection elements in order to create the constructive interference based on the incoming signal's angle of incidence on the receiver.
Traditionally, phased array systems have been common in RADAR systems. These systems operate in the radio frequency regime, in the Megahertz to GigaHertz frequencies. More recently, optical phased array systems are being proposed and built.
For example, the present inventors have proposed a variant of traditional phased array systems called Zero Optical Path Difference Phased Arrays. These are described in US Pat. Appl. Pub. No. 2016/0245895 A1, which is incorporated herein by this reference in its entirety. This concerns zero-optical-pathlength-difference optical phased arrays built with essentially planar photonic devices. They were proposed to be used to determine a direction to an incoherent optical source, such as a star, in one example. The zero-optical-pathlength-difference phased arrays were optically connected to interferometers.
At the same time, other have proposed to use systems of microlenses, waveguides and output lenses for imaging applications. U.S. Pat. No. 7,187,815 describes wavefront relay devices that sample an incoming optical wavefront at different locations, optically relay the samples while maintaining the relative position of the samples and the relative phase between the samples. The wavefront is reconstructed due to interference of the samples, but on a smaller scale, i.e., reduced pupil. In one application, the device could function as a telescope but with negligible length.